Chrome 扩展程序获取 POST 请求数据

Question

我正在尝试使用 chrome 扩展获取 POST 请求的 formData 。我正在使用以下 manifest.json 文件和 background.js 文件。但是，当我 console.log requestBody 时，我看不到网站发送的 formData。如何获取表单元素？

manifest.json

{
  "manifest_version": 2,
  "name": "Form Data",
  "description": "Looks at some form data.",
  "version": "0.9",
  "background": {
    "scripts": ["background.js"]
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ]
}

background.js

chrome.webRequest.onBeforeRequest.addListener(
    function(details) {
        if(details.method == "POST")
            console.log(JSON.stringify(details));
    },
    {urls: ["<all_urls>"]},
    ["requestBody"]
);

响应示例：

{"frameId":0,"initiator":"https://example.com","method":"POST","parentFrameId":-1,"requestBody":{"raw":[{"bytes":{}}]},"requestId":"13910","tabId":430,"timeStamp":1645826234368.5469,"type":"xmlhttprequest","url":"https://www.example.com/api/v4/login"}